ESTIMATION OF HERITABILITY OF LIPIZZANER HORSES FOR MORPHOLOGICAL TRAITS BY MEANS OF VARIOUS METHODS

Heritability of morphological traits of Lipizzaner horses in Croatia w as estimated by various methods. Heritability for withers height, obta ined by the method of intraclass correlation, was somewhat higher (h(2 ) = 0.32) compared to the method of regression and the REML method (h( 2) = 0.29 and 0.26, respectively). The same was estimated for chest gi rth and cannon bone circumference. For the three investigated traits t he variance within sires was higher than the variance between sires. T he heritability obtained by the ML method for.withers height of mares exceeds the heritability estimated by the REML method for 0.01. For th e chest girth, the estimated heritabilities by the ML and REML method show the same value. The heritability of the cannon bone circumference of mares estimated by the ML method is 0.02 higher than the heritabil ity estimated by the REML method. The average heritability for body me asurements at foaling and at six months' of age increased with the inc rease of foaling number. For the first and second foaling heritability was h(2) = 0.27, and for the first to the fifth foaling it was h(2) = 0.34. The same trend was found for the heritability level of chest gi rth and cannon bone circumference at foaling and at six months of age. This points to slightly higher influence of genetic factors upon vari ability bf the analysed morphological traits in later foalings.